The present invention relates in general to a drilling apparatus for underground works.
The following discussion of related art is provided to assist the reader in understanding the advantages of the invention, and is not to be construed as an admission that this related art is prior art to this invention.
When introducing boreholes in the ground and in particular when horizontal drilling is involved in which a borehole, starting from the surface or a starting shaft provided in the ground, is made horizontally or slantingly into the soil, drilling rod assemblies are typically used comprised of individual rod sections which are successively connected with one another in accordance with the progress of the drilling operation. In this way, relatively short rod sections enable the introduction of boreholes which extend sometimes several hundred meters.
Attachment of a new rod section to the drilling rod is carried out automatically in many drilling apparatuses. The drilling apparatuses include for that purpose typically a rod magazine to store a plurality of rod sections, as well as a rod transfer device which grabs a rod section liberated from the rod magazine to position it in the drill rig of the drilling apparatus in such a way as to arrange the longitudinal axis of the respective rod section in coaxial relationship to the longitudinal axis of the drilling rod. The thus positioned rod section can be gripped by means of a rotary drive and moved towards the free end of the rod section and then screwed with the rear end of the drilling rod through rotation of the rod section.
U.S. Pat. No. 6,969,222 discloses a drilling apparatus in which a rod magazine is positioned above and laterally of the drilling rod axis and the individual rod sections are transported from the transfer position below the rod magazine by means of a pivot arm into the drilling rod axis. This prior art has the drawback that a movement of the rod section to be newly attached towards the rear end of the drilling rod requires a shift of the rod section in the mounting of the rod transfer device, causing high wear of the rod section as well as of the transfer device, in particular when clamping the rod section in the rod transfer device is involved.
It would therefore be desirable and advantageous to provide an improved drilling apparatus to obviate prior art shortcomings and to significantly reduce wear of a rod section and the mounting of a transfer device, when transferring the rod section in the drilling rod axis.